Apparatus for rotating a tubing string of a pumping wellhead are commonly referred to as "rotating wellhead systems". The tubing string is rotated in order to reduce wear on the inside of the tubing caused by sucker rod movement.
U.S. Pat. No. 5,139,090 which was issued to Land in 1992 provides an example of a rotating wellhead system. The Land reference describes a tubing rotator attached to the wellhead by means of an adaptor. An upper swivel is positioned above the tubing rotator and a lower or downhole swivel is positioned below the tubing rotator.
Rotating wellhead systems, such as illustrated in the Land, reference have a number of problems. One problem is the entry of water through the top of the unit. If such water freezes, it destroys the rotating wellhead system. Another problem relates to the danger that excessive torque will be placed upon a fluid flow line rotating wellhead system. A final problem is that height that such rotating wellhead systems add to the wellhead. It is desirable that the rotating wellhead system be as compact as possible, so not to make it difficult for a person to perform a ground level check on the wellhead.